1. Technical Field
The present invention relates to a liquid ejection head having a piezoelectric element that causes a pressure change in a pressure generating chamber communicating with a nozzle opening and has a piezoelectric layer and an electrode for applying a voltage to the piezoelectric layer, a liquid ejection device, a piezoelectric element, and a piezoelectric material.
2. Related Art
Mentioned as piezoelectric elements for use in liquid ejection heads is a piezoelectric element having a structure where a piezoelectric material that exhibits an electromechanically conversion function, such as a piezoelectric layer containing a crystallized dielectric material, is sandwiched between two electrodes. Such a piezoelectric element is mounted on a liquid ejection head as, for example, an actuator device in a bending vibration mode. Mentioned as a typical example of the liquid ejection head is, for example, an ink jet recording head in which a part of a pressure generation chamber communicating with a nozzle opening for discharging ink droplets is constituted by a diaphragm and which discharges ink in the pressure generation chamber as ink droplets from the nozzle opening by deforming the diaphragm by the piezoelectric element to pressurize the ink. Mentioned as the piezoelectric element to be mounted on such an ink jet recording head is, for example, a piezoelectric element formed by forming a uniform piezoelectric material layer throughout the entire surface of the diaphragm by a film formation technique, and then cutting the piezoelectric material layer into a shape corresponding to the pressure generation chamber by a lithography method to be independent for every pressure generation chamber.
The piezoelectric material for use in such a piezoelectric element is required to have high piezoelectric characteristics (distortion level), and lead zirconate titanate (PZT) is mentioned as a typical example (JP-A-2001-223404).
However, a piezoelectric material in which the lead content is reduced has been desired from the viewpoint of environmental problems. Examples of piezoelectric materials not containing lead include BiFeO3 which is a perovskite type complex oxide represented by, for example, ABO3. Such a BiFeO3-based piezoelectric material containing Bi and Fe has problems in that the insulation properties are low and a leakage current occurs. Such problems similarly occur in other piezoelectric elements without being limited to the liquid ejection head typified by the ink jet recording head.